New research from the Monell Center reveals that
simply believing that an odor is potentially harmful
can increase airway inflammation in asthmatics for
at least 24 hours following exposure. The findings
highlight the role that expectations can play in
health-related outcomes.
'Asthmatics often are anxious about scents and
fragrances. When we expect that an odor is harmful,
our bodies react as if that odor is indeed harmful,'
said study lead author Cristina Jaén, PhD, a Monell
physiologist. 'Both patients and care providers need
to understand how expectations about odors can
influence symptoms of the disease.'
The airways of asthmatics are sensitive to
‘triggers’ that further inflame and constrict the
airways, making it difficult to breathe.
There are many different types of triggers,
including pollen, dust, irritating chemicals, and
allergens. Strong emotions and stress also can act
to trigger asthma symptoms.
Because asthma has no cure, it is important for
individuals with the disease to understand how to
manage their symptoms to help prevent severe asthma
attacks.
Many health organizations list scents and fragrances
as asthma triggers, leading patients to become
anxious when exposed to environmental odors. The
current research was conducted to determine whether
odor-triggered asthma symptoms can be elicited or
worsened by associated negative expectations.
In the study, published online ahead of print in the
Journal of Psychosomatic Research, 17 individuals
characterized as moderate asthmatics were exposed to
the odor phenylethyl alcohol (PEA) for 15 minutes.
Often described as rose-smelling, PEA is regarded as
a ‘pure’ odorant with no associated physiological
irritant qualities.
Eight subjects were told that the odor had potential
therapeutic properties, while nine were told that it
potentially could cause mild respiratory problems.
During odor presentation, the subjects rated the
odor’s sensory properties, including intensity,
irritancy, and annoyance.
Measures of lung function and airway inflammation
were collected before and immediately after exposure
and again at two hours and 24 hours post-exposure.
Subjects’ beliefs about the odor, specifically
whether it was potentially harmful
(asthma-triggering) or therapeutic, influenced both
their psychological and physiological responses to
odor exposure.
Individuals who were told that the odor was
potentially harmful rated it as more irritating and
annoying as compared to those who thought it might
be therapeutic.
In addition, airway inflammation increased
immediately following odor exposure in subjects who
believed the odor might be harmful and remained
elevated 24 hours later.
'Introducing a negative bias led to a rapid change
in airway inflammation,' said senior author Pamela
Dalton, PhD, a cognitive psychologist at Monell.
'What really surprised us was that this response
lasted for over 24 hours.
The increased inflammation during this period likely
makes asthmatics more sensitive to other triggers.'
There was no increase of inflammation when the odor
was characterized as therapeutic, even in
individuals who described themselves as sensitive to
perfumes and other odors.
The findings suggest that some fragrance effects on
asthma symptoms may be related to the expectation of
harm as opposed to chemical properties of the odor.
'It’s not just what you smell, but also what you
think you smell,' said Jaén.
Looking forward, the researchers want to identify
the biological mechanisms that connect expectations
to airway inflammation. They also intend to explore
whether a reverse phenomenon also exists. Dalton
asks, “Can we improve health outcomes by reducing
concern or fear in a disease where emotional arousal
is counter-productive?”
The Monell Center is the world’s only independent,
non-profit scientific institute dedicated to
interdisciplinary basic research on the senses of
taste and smell.
For more information
Monell Center
http://www.monell.org/
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